1. Field of the Invention
The present invention relates generally to powered devices for ascending and descending elevations, and particularly to a stair-climbing apparatus capable of free operation (i.e., not secured to another structure) on a flight of stairs or the like.
2. Description of the Related Art
The need for powered mechanical assistance for persons that have occasion to ascend or descend elevations has been known for a considerable period of time. This is particularly true for the elderly or infirm who have need to travel between floors of a multiple story building. The need also arises when transporting large and/or heavy articles between floors in a multiple story building, e.g., large office machines, such as console copiers, office or other furniture, etc.
Accordingly, elevators were developed well over one hundred years ago, and escalators were developed somewhat later. However, elevators and escalators require that the building structure provide for such devices, or the building structure must be modified extensively after completion in order to accommodate such lift devices.
As a result, various devices have been developed in the past for negotiating stairways and the like. Some of these devices are permanently installed along or on stairways to travel up and down the stairway. Often, these permanently installed machines also required modification of the building structure for their installation. Still other portable devices have been developed as well. Most, if not all, such devices require that the stairs have a constant pitch or slope in order for the device to function. If the stairs have a different pitch or slope between landings or between stories, most such devices are incapable of proceeding beyond the first flight of stairs.
Thus, a stair-climbing apparatus solving the aforementioned problems is desired.